Spark Plugs

Flip_x · Post by **Flip_x** » Tue Apr 27, 2004 8:17 am

Whats a good spark plug to use?? does the NGK iridium IX any good? anyone tried it yet? and whats the best range cold or heat wise for a N/A 90 legacy and does have the diamond in it hehe

anyways i just wanna do a tune up and see if it helps any. thx peeps

vrg3 · Post by **vrg3** » Tue Apr 27, 2004 8:30 am

Here's where all the spark plug knowledge on this board is:

http://bbs.legacycentral.org/viewtopic.php?t=634

boostjunkie · Post by **boostjunkie** » Tue Apr 27, 2004 1:56 pm

FWIW, my car came stock from the factory with NGK iridiums. I swapped them out for some NGK coppers as soon as I took delivery of the car!!

elkaboom · Post by **elkaboom** » Tue Apr 27, 2004 6:07 pm

I'm pretty sure irridium plugs weren't even available back in 90. IIRC, the irridium core plugs have only been around for a couple years. I could be wrong, though.
In any event, the previous owner must have installed them; you did a good thing by using the NGK coppers -they provide better conductivity than irridium or platinum. The denser core material only increases the life of the plug, which in my estimation, is a negligable consideration anyway.
Stick with the NGK V-Powers.

THAWA · Post by **THAWA** » Tue Apr 27, 2004 6:13 pm

I think he was talking bout the celica. I thought the same thing at first though

boostjunkie · Post by **boostjunkie** » Tue Apr 27, 2004 8:04 pm

elkaboom wrote:I'm pretty sure irridium plugs weren't even available back in 90. IIRC, the irridium core plugs have only been around for a couple years. I could be wrong, though.
In any event, the previous owner must have installed them; you did a good thing by using the NGK coppers -they provide better conductivity than irridium or platinum. The denser core material only increases the life of the plug, which in my estimation, is a negligable consideration anyway.
Stick with the NGK V-Powers.

Note what car I have now

elkaboom · Post by **elkaboom** » Tue Apr 27, 2004 10:03 pm

D'oh!

vrg3 · Post by **vrg3** » Wed Apr 28, 2004 12:18 am

I thought iridium and platinum plugs had slightly different purposes.

Platinum plugs do just have longer service intervals, and I agree that's not really much of a selling point, but I thought iridium plugs had the potential to outperform copper because the very sturdy electrode could have a really really tiny tip which can improve ignition.

evolutionmovement · Post by **evolutionmovement** » Wed Apr 28, 2004 7:43 am

I heard the same thing.

Steve

93Leg-c · Post by **93Leg-c** » Wed Apr 28, 2004 8:24 am

Ditto.

Sir Yach-o · Post by **Sir Yach-o** » Wed Apr 28, 2004 8:50 am

I found an article in some import tuner mag where they dropped Denso iridium plugs into a Supra, and came out with 7 or 8 more hp, with that being the only mod from stock, FWIW. Doesn't sound so bad.

boostjunkie · Post by **boostjunkie** » Wed Apr 28, 2004 1:40 pm

vrg3 wrote:I thought iridium and platinum plugs had slightly different purposes.

Platinum plugs do just have longer service intervals, and I agree that's not really much of a selling point, but I thought iridium plugs had the potential to outperform copper because the very sturdy electrode could have a really really tiny tip which can improve ignition.

I've heard that too, but when I took out the iridium plugs they were pretty well sooted. The longer service intervals for the iridiums (they better be considering you pay an arm and a leg for them) might be a plus, but they do get sooted over time, which leads me to believe that they wouldn't be as beneficial in the long run.

I personally would rather stick to changing copper ones every 5000-10000 miles and have some pretty comparable performance than a 30,000 mile iridium, that might have some decreased efficiency due to sooting.

But to each his/her own.

vrg3 · Post by **vrg3** » Wed Apr 28, 2004 4:08 pm

Yeah, I was just saying what I had read. For all I know it was all just marketing jibberish.

I should also point out that I've also read about iridium plugs with extremely small electrodes suffering from electrode breakage, which is obviously very bad.

Sir Yach-o, do you know what plugs they had in there before? And whether they reset the ECU between tests? If they had replaced 10,000-mile-old copper plugs with brand new copper plugs they probably would have seen an improvement even without switching plug types... And without resetting the ECU it can be hard to get consistent and comparable results.

boostjunkie - Yeah, I'm with you. I wouldn't leave a plug in my engine for 30,000 miles anyway (and don't some platinum ones "last" 100,000 miles?). Steel and aluminum shouldn't be left in contact that long under those temperature and pressure conditions anyway. And if you don't periodically read your plugs, you lose a key bit of information on your engine's health.

boostjunkie · Post by **boostjunkie** » Wed Apr 28, 2004 5:48 pm

I think the plats and irids are both 60,000, but I could be wrong.

evolutionmovement · Post by **evolutionmovement** » Wed Apr 28, 2004 7:24 pm

I usually keep coppers for around 20K. I don't see a need for long service plugs in these cars as they are very easy to change and the coppers are cheap. If you had a car like the new Eclipse POS where the intake manifold has to be removed to replace the plugs then I'd say go for the platinums.

Steve

entirelyturbo · Post by **entirelyturbo** » Thu Apr 29, 2004 5:23 am

I still think V-powers give the best performance for the money. Iridiums have longer service intervals, sure. But one set of iridium plugs costs me as much as 6 sets of V-Powers, so the longer service advantage is pretty much null and void.

Copper is the 2nd best conductor of electricity of any metal we know of, the 1st being silver. With that in mind, Nology makes a set of silver-tipped spark plugs about the same price as iridiums, I believe. However, silver also being a soft metal, I doubt they will last long.

Someone should try them out for the sake of experimentation

boostjunkie · Post by **boostjunkie** » Thu Apr 29, 2004 2:05 pm

subyluvr2212 wrote: Someone should try them out for the sake of experimentation

If you fund the experiment, I'll volunteer my car to be the test bed

skid542 · Post by **skid542** » Sun May 02, 2004 12:57 am

Forgive my ignorance here, but what is the difference between the hot/cold/stock plugs? I understand that it is a temperature difference between them but I don't understand exactly how it effects the performance of my engine or the reliablity of my engine. School gets out in two weeks and among the list of little tune ups the plugs are definately on the list. Thanks.

Lee

P.S. The crank pulley fix is still holding in just fine. I check it everytime I get gas and check my fluids.

vrg3 · Post by **vrg3** » Sun May 02, 2004 1:53 am

The heat range of a plug just represents how easily the plug's body conducts heat away from the center electrode (and into the cylinder head, where coolant can take it away). A "hot" plug doesn't conduct much heat, and a "cold" plug conducts a lot of heat.

You need to maintain a certain amount of heat in the plugs to maintain good combustion. Too little heat results in fouling of the plugs and incomplete combustion. Too much results in detonation.

You always want to use an appropriate heat range for your engine's combustion characteristics. If your combustion temperatures tend to be very high, you need a colder plug. If they tend to be very low, you need a hotter plug.

Unless your motor's very highly modified it's probably best to stick with the stock heat range. If you're running very high boost it might be good to go one or two ranges colder. You pretty much just have to experiment to find what range works best for you, just like you have to experiment to find what gap works best for you.

skid542 · Post by **skid542** » Sun May 02, 2004 6:04 am

As always you're replies are most informative. I don't have a turbo and don't have any engine modifications really so I'll be sticking with the stock but thanks for clearing things up for me.

Lee

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

Spark Plugs

Spark Plugs